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In-Situ Switching from Barrier-Limited to Ohmic Anodes for Efficient Organic Optoelectronics

Title data

Tan, Zhi-Kuang ; Vaynzof, Yana ; Credgington, Dan ; Li, Cheng ; Casford, Mike T. L. ; Sepe, Alessandro ; Hüttner, Sven ; Nikolka, Mark ; Paulus, Fabian ; Yang, Le ; Sirringhaus, Henning ; Greenham, Neil C. ; Friend, Richard H.:
In-Situ Switching from Barrier-Limited to Ohmic Anodes for Efficient Organic Optoelectronics.
In: Advanced Functional Materials. Vol. 24 (2014) Issue 20 . - pp. 3051-3058.
ISSN 1616-3028
DOI: https://doi.org/10.1002/adfm.201303426

Abstract in another language

Injection and extraction of charges through ohmic contacts are required for efficient operation of semiconductor devices. Treatment using polar non-solvents switches polar anode surfaces, including PEDOT:PSS and ITO, from barrier-limited hole injection and extraction to ohmic behaviour. This is caused by an in-situ modification of the anode surface that is buried under a layer of organic semiconductor. The exposure to methanol removes polar hydroxyl groups from the buried anode interface, and permanently increases the work function by 0.2–0.3 eV. In the case of ITO/PEDOT:PSS/PBDTTT-CT:PC71BM/Al photovoltaic devices, the higher work function promotes charge transfer, leading to p-doping of the organic semiconductor at the interface. This results in a two-fold increase in hole extraction rates which raises both the fill factor and the open-circuit voltage, leading to high power conversion efficiency of 7.4. In ITO/PEDOT:PSS/F8BT/Al polymer light-emitting diodes, where the organic semiconductor's HOMO level lies deeper than the anode Fermi level, the increased work function enhances hole injection efficiency and luminance intensity by 3 orders of magnitude. In particular, hole injection rates from PEDOT:PSS anodes are equivalent to those achievable using MoO3. These findings exemplify the importance of work function control as a tool for improved electrode design, and open new routes to device interfacial optimization using facile solvent processing techniques. Such simple, persistent, treatments pave the way towards low cost manufacturing of efficient organic optoelectronic devices.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: solvent treatment; ohmic anodes; organic photovoltaics; organic light emitting diodes; interface modification
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Junior Professorship Solar Energy > Junior Professorship Solar Energy - Juniorprof. Dr. Sven Hüttner
Profile Fields > Advanced Fields > Polymer and Colloid Science
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Junior Professorship Solar Energy
Profile Fields
Profile Fields > Advanced Fields
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
500 Science > 540 Chemistry
Date Deposited: 30 Aug 2017 06:14
Last Modified: 30 Aug 2017 06:14
URI: https://eref.uni-bayreuth.de/id/eprint/39202